Jamestown, ND 58405 Frost Dates
When can you plant in Jamestown, ND?
Typically, the last spring freeze lands around 05/11, roughly 256 days out. The first fall frost typically arrives around 09/28, about 138 frost-free days later.
Zone 4b (-25 to -20°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Jamestown, not a forecast for this year.
What to do before the first frost
About 4 weeks of growing season left in Jamestown before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 05/11 isn't a guarantee
05/11 is the middle of 30 years of NOAA records, not a promise. Plant by 04/28 and you're betting against frost in roughly 9 years out of 10. 05/24 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Jamestown compares
About 138 days separate Jamestown's last and first frost, putting it 37,359 of 40,283 ZIP codes nationally. Within ND, it ranks 183 of 405.
Learn more
zone vs. frost date covers why Zone 4b and Jamestown's frost date answer different questions. the frost range covers how to read the range around Jamestown's dates instead of trusting one.